This invention relates to a new process for preparing polyamides. This process comprises reacting an alpha, beta-unsaturated nitrile with at least one alpha, beta-unsaturated carboxylic acid or ammonium salt thereof.
The preparation of a polyamide from acrylonitrile and water is disclosed in U.S. Pat. Nos. 3,629,203 and 3,499,879. Moreover, the preparation of a polyamide from an alpha, beta-unsaturated acid or ammonium salt thereof is disclosed in U.S. application Ser. No. 032,327, now U.S. Pat. No. 4,283,524. Surprisingly, applicants have discovered that combining these reactants in a single system produces high yields of a polyamide which has particularly good physical properties.
There are several advantages in producing polyamides by the process of the instant invention. First, the water of condensation produced by the polymerization of the alpha, beta-unsaturated carboxylic acid or salt thereof is consumed internally by the alpha, beta-unsaturated nitrile, thus avoiding or reducing the requirement for vacuum stripping of the water. Second, the polyamides produced by the process of this invention are more crystalline than those produced by the prior art methods. Third, it is possible to obtain a polyamide which is melt stable, i.e. melts without decomposition, by the process of this invention.